Reboulia hemisphaerica (L.) Raddi

  • Authority

    Bischler, Hélène, et al. 2005. Marchantiidae. Fl. Neotrop. Monogr. 97: 1--262. (Published by NYBG Press)

  • Family

    Aytoniaceae

  • Scientific Name

    Reboulia hemisphaerica (L.) Raddi

  • Type

    Type. Europa (syntype, OXF, n.v.).

  • Synonyms

    Marchantia hemisphaerica L., Grimaldia hemisphaerica (L.) Lindenb.

  • Description

    Species Description - Thallus 3-8 mm wide, light green with narrow, purplish borders that are often lobulate-sinuose and ascending; branching dichotomous, ventral and by apical adventitious branches. Epidermal cells with thin to slightly thickened walls and conspicuous trigones. Epidermal pores 190-250 µm diam., bounded by 4-6 concentric rings of 5-9 cells, radial walls usually strongly thickened. Air chambers in 5-6 layers. Scales purplish, imbricate, with oil cells and marginal papillae, with 2-3 filiform appendages, 2-3 cells wide basally, with row of 2-4 cells apically. Monoecious. Antheridia in irregular groups or in cushions bounded by ±; numerous, purplish scales, in neotropical specimens usually behind archegoniophore. Archegoniophore stalk 6-25 mm long; receptacle 4- to 7-lobed, hemispherical, with compound epidermal pores on dorsal side. Spores yellowish brown, 60-90 µm diam., areolate on both faces, with 4-5 large areoles across diam, and broad wing, ridges of areoles and wing tuberculate. Elaters with 2-3 helical bands. Gametophytic chromosome number n = 9 or 18.

  • Discussion

    The species grows usually in dense colonies on humid or wet clay, sand, or sandy clay, overlying limestone, dolomite or other calcareous rocks, in rock crevices or stone walls, on exposed riverbanks, in grassland, on roadsides, under scattered shrubs, or in open forests, from sea level to 4000 m.

    Reboulia hemisphaerica is easily distinguished by its ventral scales having several filiform appendages.

    The species comprises at least 3 genetically distinct but morphologically hardly differentiated, allopatric components that may deserve specific status: 2 haploids, 1 from Europe and Africa, found also in S United States, a second from Japan, and a polyploid from Australasia (Boisselier-Dubayle et al., 1998). The neotropical specimens have not been examined genetically. Whether they belong to one of these 3 components or to additional ones remains to be investigated.

    None of the seven subspecies described by Schuster (1992b) has been recorded or seen from the Neotropics.

    Distribution and ecology: Reboulia hemisphaerica is widespread in warm-temperate areas all over the world. It is recorded from Europe up to 61°N, the Mediterranean area, Macaronesia, tropical E and S Africa, and SW Asia. The E Asiatic and Australasiatic records (E Asia, India, Sri Lanka, Japan, Taiwan, tropical Asiatic Islands, New Caledonia, New Zealand, Australia, Tasmania) are genetically distinct and might belong to other species (Boisselier-Dubayle et al., 1998). In the United States the species has been recorded from 42 (out of 49) states. In the Neotropics, the species is quite common in SE Brazil but rare elsewhere. It is known from Mexico (Chihuahua (A. Whittemore, pers. comm.), Chiapas, Colima, D. F., Durango, Hidalgo, Mexico, Morelos, Nuevo Leon, Oaxaca, Puebla, Querétaro, Socorro Is., Tlaxcala, Veracruz), Bermuda, Cuba, Haiti, Jamaica, Puerto Rico, Brazil (Rio Grande do Sul), Bolivia (Rusby, 1895), Chile (Los Lagos (Reimers 1926), Magellanes, Santiago, Juan Fernandez), Argentina (Buenos Aires (Hássel de Menéndez, 1963; Grolle (1983b), Chubut (Hássel de Menéndez, 1963), Misiones, Neuquén, Rio Negro (Hássel de Menéndez, 1963), Tierra del Fuego (Engel 1976)), and Uruguay.